Many if not most computer games expect you to use a mouse + keyboard. Driving games expect wheels and flight sims expect joysticks, which are fair enough, but it seems to me that many games get thrown by the simplest of control changes. Swapping to left-handed, for instance, threw Runes of Magic. And heaven forfend that you not use a mouse: Left for Dead 2 is much more difficult with a trackball, but I don’t use mice if at all possible - I’ve had twinges in my hands before. The scenario editor for Command & Conquer 3 demands a scroll wheel. And it goes on.
What testing with non-standard devices and controls is actually done?
I think it’s safe to say that there is no “standard”; I bet Blizzard does plenty of testing with left handers and trackballs, whereas outfits working on tighter schedules and more limited budgets may be more tempted to let some of this stuff slide. There’s definitely a sense of “acceptable losses” in the PC world, since it’s essentially impossible to test with every bizarre hardware configuration - does anyone test their software to see how it performs with any of the various options for disabled users? Probably not. And I think it’s safe to say that most FPS game manufacturers aren’t losing a lot of income because they haven’t tested their software with devices that allow you to mimic a mouse by moving your head. I was unable to find any data on what percentage of PC users actually use trackballs in my one minute google search, but anecdotally, I think the percentage is pretty small, and most developers may see not testing with them to be within the realm of the acceptable (Unless they happen to have a staffer in house who loves them). Left handedness is probably similar.
So to sum up: Some companies probably test with this stuff, but it’s by no means the rule.
There will be *testing *to make sure the game functions with alternate controls, but there will be very little tuning.
Generally games are tuned to one particular control set. Other control sets are included as options for the player, but even if they substantially alter the difficulty of the game, generally no effort is made to create an alternate balance.
The reason for this is that balancing a game is complicated and time-consuming. It takes weeks or even months to find the particular sweet spot in the difficulty/timing/cadence that gives the best experience. Doing it multiple times for alternate control sets is not an efficient use of the dev team’s time.
Still, some of the problems with “non-standard setups” are something which is a matter of game design/port strategy.
I have an edition for Spain of Prince of Persia: Warrior Within for PC; it’s a console port. Each action is bound to a single key, the keybinds can not be changed and they require a US keyboard setting. The numpad and cursor keys might as well be non-existant, whereas on games with double binds, ASWD and the cursors are usually equivalent by default allowing me to take a sip with my left hand while moving with the right, or scratch the small of my back with the right while moving with the left. Why did the people porting that game not think “there is more than one keyboard configuration in the planet” or “most people happen to have two hands”? No idea, but I imagine a game with flexible keybinds would be easier to adapt for “non-standard setups” than one which expects people in Spain to change keyboard layout in order to be able to play the game (or worse: France or Russia, whose keyboards aren’t even qwerty). Note that when I got it, analog keypads for PCs were a specialty item (at least locally to me), you pretty much had to know someone who knew someone, in order to get one; nowadays you can buy one in any store but still… would that game have been able to recognize one? It definitely would not have allowed me to bind the new controller’s keys, so what then?
It’s not about alternate control sets: it’s about flexible ones.
I don’t really think this is even the same issue as the one in the OP; The former is just general inflexibility, and is just about as annoying for anyone who finds the initial control mappings etc unsatisfactory. Certainly, one with a flexible keyboard setup gets you around some issues, and is generally a good idea, but that’s different from really supporting any sort of alternate input method.
Goes a good way towards it, though. The case I described treated any non-US keyboard as an “alternate input method”, it’s extreme but not the only time I’ve encountered it… just the one time I’ve encountered it in a big-name game.